9. Friend Time
By extension, not having to deal with guilds and random pick-up groups, Borderlands did a great job of distilling what was really fun about multiplayer gaming - playing with your friends. The number of times I've been on a WoW server or begun a new MMO with the intention of playing with a friend only to get lost amongst our own loot obsessions and guild problems without ever actually getting to play together is almost countless. Borderlands strips all that away. Playing, at maximum, with three other people is a great way to actually interact in a multiplayer environment without getting distracted by other people and the time they consume.